Prior attempts have been made to automate camera movement in order to achieve special effects in motion picture photography. In achieving special effects, a camera is typically focused upon a model and moved relative thereto, while always pointing at the model. The model itself may likewise be moved, especially in roll, pitch and yaw. The resulting effects, when photographed, simulate observation of a much larger object, viewing the object from ever changing fairly distant vantage points.
One early automated camera control system is described in U.S. Pat. No. 2,648,252. In this system, the relative position and orientation of a camera and subject were varied automatically through a predetermined pattern of movement. The original motion pattern was produced from manual operation of conventional camera hand wheels. One unit, or channel, of a recording-repeating mechanism was provided for each component or axis of motion. The actual record of the relative motion between camera and subject in terms of coordinates along any axis was made by inscribing a line lengthwise on a moving record strip or tape. The transverse variations in position of the line on the strip corresponded at any instant to the value of the coordinate on the axis involved. After recording a record groove, a repeating arm followed the previously prepared record. The signals received were coupled to a camera servomotor control for the axis involved.
One significant limitation of this system is that movement of the camera in the first instance in order to produce the recorded coordinate groove in the tape required manual movement of the camera. The system required great skill of the camera man producing the tape, and a number of practice runs were undoubtedly necessary to achieve a smooth, flowing movement of the camera relative to the subject. Even with extensive practice, however, the system was subject to imperfections in camera movement that might or might not have appeared during the initial practice runs. Moreover, the record tape produced was unalterable once recorded, and could not be edited.
More recent systems have substituted cassette tape data storage which could be edited repeatedly in place of the prior record strip or tape. In this way, satisfactory segments of camera movement could be retained while unsatisfactory segments could be redone and the revised motion recorded in place of the original unsatisfactory segment. Nevertheless, manual manipulation of the camera throughout its course of movement in the first instance was required, even though remote joy stick controls were substituted for the earlier hand wheels. Furthermore, cassette tape data storage was limited to two minutes of frame sequences. Although a remote focusing servo control was utilized to prevent the camera man from touching and jiggling the camera during filming, manipulation of the remote focusing control was manual. Furthermore, the stepper motor controls of this later system did not provide any basis for correcting for errors in movement. That is, the camera was ordered to progress along particular coordinate paths, although due to mechanical imperfections in the control system, the camera was free to deviate from these paths with no way of detecting or compensating for these deviations.